It's quite simple. A larger sensor/film will be less critical of the flaws in the lens infront of it. IE: it's make bad lenses not look so bad.

Not entirely accurate.

It would be equally sensible to claim that a small sensor will be less critical of the flaws in the lens infront of it. Lenses tend to perform their worst in corners, and if the sensor does not record anything in corners, you avoid such problems.

Despite all the acrimony in this thread, there is some interesting stuff. I would not dispute that that a FF is better than an APS-C with a 1.6xshorter focal length lens so that the whole picture area has the same field of view. I am interested in photography at super telephoto distance where crop factor is thought to be important. So, I decided to do a rough and ready test of FF vs APS-C doing my favourite hobby, taking photos of birds with a 300mm f/2.8 II +2xTC III. Accordingly, I took my ancient 7D and my new 5DIII and did the Old Grey Heron Test (parodying http://en.wikipedia.org/wiki/The_Old_Grey_Whistle_Test). The heron did his bit, stayed in one place long enough so I could switch bodies. The 7D was at iso 400 and the 5DIII at 640. Consistent with my other recent experience, the IQ of the 5DIII makes up for the crop factor loss of 1.5 fold as the two centre crops were quite similar. The 7D was noisier, as expected. I usually use it at iso 320 or less. At great length extremes, the 7D does have an advantage but otherwise the FF is just as good for bird photography with the same lenses, and the closer you get to the target, the better it should be. It will be interesting to see when the 7D II comes out with more modern technology if it can overtake the 5DIII in the telephoto range,

Consistent with my other recent experience, the IQ of the 5DIII makes up for the crop factor loss of 1.5 fold as the two centre crops were quite similar. The 7D was noisier, as expected. I usually use it at iso 320 or less. At great length extremes, the 7D does have an advantage but otherwise the FF is just as good for bird photography with the same lenses, and the closer you get to the target, the better it should be. It will be interesting to see when the 7D II comes out with more modern technology if it can overtake the 5DIII in the telephoto range,

^^ This is why I don't use my 7D anymore... Add to that the case of the 600/4, where the FF 1D X will autofocus with a 2x TC for 1200mm focal length, compared to the 7D which needs f/5.6 for phase AF and therefore is limited to the 1.4x TC and a FF-equivalent of 1344mm - an effective 'crop factor benefit' of only 1.12x.

From my understanding of your posts it seems to me that you think the pixels you see on your screen are the same ones on your sensor.

Eh, you might be the one with a bit of confusion as to what a pixel is.

When you're looking at a 100% crop of an image, the pixels on your monitor are a (close to) perfect representation of the pixels on the sensor, just magnified a Brazilian times. There are caveats, of course, insofar as there are different color gamuts and luminance mapping and what-not, but those have no practical bearing on the discussion.

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Also the actual size of the image projected onto the sensor is creating another confusion here. Yes it's true to say the recorded image as it falls on the sensor is larger on a larger sensor, but the ability to record it accurately comes down to lenses and pixel efficiency, so having a ( slightly ) larger light image on the sensor does not necessarily mean it has been recorded more accurately.

As with so many others, you're significantly overstating the importance of the megapickles.

Can a smaller format system produce sharper images than a larger format system? Yes, but not by merely matching the (in the case of digital) total pixel count of the larger format. You need at least the same number of megapickles to make up for the quantization advantage of the larger format, but you then need even more (resolution, optics quality, whatever) to make up for the surface area advantage of the larger format.

And this is where film is such a useful example to bring into the mix. Let's say you developed some fantastic new film that was so much better than the film currently being used in 120 film that it made a 135 camera produce images as good as those from 645. Great news! But the very next thing that's going to happen is that said film is going to get packaged into a 120 roll...and now the 645 images are going to be just as much better. Indeed, the 645 images with the new film are going to be as good as 4x5 images with the old film...but, again, the large format shooters are going to be all over the new film, and the 4x5 images are going to be as good as 8x10, and the 8x10 images are going to be better than original reality.

That's the exact same thing we see with digital formats, except that the expense of scaling up film formats is much gentler than the expense of scaling up new digital formats.

So please, by all means. Support enhanced image quality in smaller formats. But what makes you think those same enhancements aren't on their way to the larger formats as well?

Cheers,

b&

To quote a great luminary: "Don't underestimate the power of the megapickle." (Darth Vader, when discussing the 7D vs the 1D4 with the Emperor)

A few extra megapixels goes a long long way...

Hmmm, I'm lost. The 1D4 has much better IQ than the 7D. Or was that a joke? If so, good one!

That Gray Heron test confirms my own experience. I own both a 7D and a 5D Mark iii. I find that the Mark iii produces consistently sharper photos, in part because of its superior autofocus (much superior!) and also because of its noise handling ability. I routinely shoot at ISO 320 with my 7D and at 640 with the 5D Mark iii. The vastly superior technology of the Mark iii more than compensates for the need to crop.

Really great article, Plamen. It proves all the sane stuff in this thread: FF beats out crop when each sensor covers the same field with different focal length lenses etc but crop and FF are quite similar when they have the same pixel density and are with the same high quality lens.